C# 在 setter 方法上添加验证

发布于 2024-11-09 16:20:51 字数 301 浏览 2 评论 0原文

我在 C# 中定义了几个变量：

public String firstName { get; set; }
public String lastName { get; set; }
public String organization { get; set; }

我想要的是在尝试设置值时向这些方法添加验证。假设您要为firstName设置一个值，i应该通过正则表达式来实际设置，否则应该抛出异常。是否可以使用这种“短语法”构建，或者我应该使用标准（如 JAVA 中的）getter 和 setter 并在那里验证数据？

原文

I have a a couple of variables that i define in C# by:

public String firstName { get; set; }
public String lastName { get; set; }
public String organization { get; set; }

What i want is to add validation to these methods when you try to set a value. Lets say your going to set a value for firstName, the i should pass thrue a regexp to actuelly be set, otherwise an exception should be thrown. Is this possible to build with this "short syntax" or should I go for standard (like in JAVA) getters and setters and in there validate the data?

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看春风乍起 2024-11-16 16:20:51

如果要在设置属性时进行验证，则需要使用非自动属性（即手动定义的 get 和 set 方法）。

但另一种验证方法是将验证逻辑与域对象分开。

class Customer {
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Organization { get; set; }
}

interface IValidator<T> {
    bool Validate(T t);
}

class CustomerValidator : IValidator<Customer> {
    public bool Validate(Customer t) {
        // validation logic
    }
}

然后，您可以说：

Customer customer = // populate customer
var validator = new CustomerValidator();
if(!validator.Validate(customer)) {
    // head splode
}

这是我更喜欢的方法：

客户不应该负责验证自己的数据，这是另一个责任，因此应该住在其他地方。
不同的情况需要对同一域对象使用不同的验证逻辑。

If you want to validate when the property is set, you need to use non-auto properties (i.e., manually defined get and set methods).

But another way to validate is to have the validation logic separate from the domain object.

class Customer {
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Organization { get; set; }
}

interface IValidator<T> {
    bool Validate(T t);
}

class CustomerValidator : IValidator<Customer> {
    public bool Validate(Customer t) {
        // validation logic
    }
}

Then, you could say:

Customer customer = // populate customer
var validator = new CustomerValidator();
if(!validator.Validate(customer)) {
    // head splode
}

This is the approach I prefer:

A Customer should not responsible for validating its own data, that is another responsibility and therefore should live elsewhere.
Different situations call for different validation logic for the same domain object.

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一刻暧昧 2024-11-16 16:20:51

您现在拥有的称为“自动属性”，并且仅执行简单的“获取/设置”。为了自定义 get 或 set 的行为，您需要将属性转换为字段支持的属性：

private string _firstName;
public string FirstName 
{ 
    get {return _firstName;} 
    set 
    {
       Validate(value); _firstName = value;
    }
}

请注意，我更改了 String > 转换为 string 并将属性名称大写，遵循公认的 C# 命名最佳实践。

What you have now are called "auto-properties," and only perform a simple "get/set". In order to customize the behavior of the get or set, you will need to convert the properties to field-backed properties:

private string _firstName;
public string FirstName 
{ 
    get {return _firstName;} 
    set 
    {
       Validate(value); _firstName = value;
    }
}

Note that I changed String to string and capitalized the property name, in following accepted C# naming best practices.

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°如果伤别离去 2024-11-16 16:20:51

我根本不会在 setter 中添加验证。相反，我会创建一个名为 validate 的函数......这样您的所有验证代码都位于一个位置，而不是分散在您的 setters 中。

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相对绾红妆 2024-11-16 16:20:51

最佳实践是应用 SRP。在单独的类中设置验证。

您可以使用 FluentValidation

       Install-Package FluentValidation

您可以通过继承 AbstractValidator为 Customer 类定义一组验证规则。:

示例：

  public class CustomerValidator : AbstractValidator<Customer> {
    public CustomerValidator() {
      RuleFor(x => x.Surname).NotEmpty();
      RuleFor(x => x.Forename).NotEmpty().WithMessage("Please specify a first name");
      RuleFor(x => x.Discount).NotEqual(0).When(x => x.HasDiscount);
      RuleFor(x => x.Address).Length(20, 250);
      RuleFor(x => x.Postcode).Must(BeAValidPostcode).WithMessage("Please specify a valid postcode");
    }

    private bool BeAValidPostcode(string postcode) {
      // custom postcode validating logic goes here
    }
  }

要运行验证器，请实例化验证器对象并调用 Validate 方法，传入要验证的对象。

   Customer customer = new Customer();
   CustomerValidator validator = new CustomerValidator();

   ValidationResult result = validator.Validate(customer);

 if(! results.IsValid) {
   foreach(var failure in results.Errors) {
       Console.WriteLine("Property " + failure.PropertyName + " failed validation. Error was: " + failure.ErrorMessage);

}
}

It's best practice to apply SRP. Set the validation in a separate class.

You can use FluentValidation

       Install-Package FluentValidation

You would define a set of validation rules for Customer class by inheriting from AbstractValidator<Customer>:

Example:

  public class CustomerValidator : AbstractValidator<Customer> {
    public CustomerValidator() {
      RuleFor(x => x.Surname).NotEmpty();
      RuleFor(x => x.Forename).NotEmpty().WithMessage("Please specify a first name");
      RuleFor(x => x.Discount).NotEqual(0).When(x => x.HasDiscount);
      RuleFor(x => x.Address).Length(20, 250);
      RuleFor(x => x.Postcode).Must(BeAValidPostcode).WithMessage("Please specify a valid postcode");
    }

    private bool BeAValidPostcode(string postcode) {
      // custom postcode validating logic goes here
    }
  }

To run the validator, instantiate the validator object and call the Validate method, passing in the object to validate.

   Customer customer = new Customer();
   CustomerValidator validator = new CustomerValidator();

   ValidationResult result = validator.Validate(customer);

 if(! results.IsValid) {
   foreach(var failure in results.Errors) {
       Console.WriteLine("Property " + failure.PropertyName + " failed validation. Error was: " + failure.ErrorMessage);

}
}

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